Cardiopulmonary apparatus and methods for use during PCI and CABG

ABSTRACT

Apparatus and methods for providing extracorporeal blood circulation and oxygenation control include multi-stage deairing of blood to provide automated cardiopulmonary replacement to sustain patient life during a medical procedure such as cardiopulonary bypass graft surgery, keyhole cardiopulmonary bypass graft surgery, percutaneous angioplasty, percutaneous stent placement, and percutaneous atherectomy.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/962,626 filed Dec. 7, 2010 and issuing May 13, 2014 as U.S. Pat. No.8,721,579, the entire disclosure of which is expressly incorporatedherein by reference.

This application is also related to U.S. patent application Ser. No.11/284,515 filed Nov. 22, 2005 entitled Apparatus For MakingExtracorporeal Blood Circulation Available; European Patent ApplicationNo. EP 04 027 855.8 filed on Nov. 24, 2004 entitled Vorrichtung zurBereitstellung eines estrakorporalen Blutkreislaufs (Device ForProviding An Extracorporeal Blood Circuit) and U.S. patent applicationSer. No. 11/554,524 filed Oct. 30, 2006 entitled Apparatus For MakingExtracorporeal Blood Circulation Available, the entire disclosure ofeach such application being expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to cardiopulmonary apparatus and methodsfor preserving the life of a patient by providing extracorporeal bloodoxygenation and circulation in which a patient's blood is introduced viaa venous connection into the extracorporeal blood circuit and is pumpedby a blood pump via different blood-conducting components to an arterialconnection from where the blood is again pumped into the patient's bloodcirculation.

The apparatus and methods are useful in a variety of medical proceduresincluding Percutaneous Coronary Intervention (PCI) such as angioplastyand drug-eluting and non-drug-eluting stent placement and CoronaryArtery Bypass Graft (CABG) procedures. The apparatus, methods, andsystems are necessary for sustaining the life of a patient while theheart is slowed or stopped during PCI or CABG.

Description of Related Art

Time is critical during PCI and CABG procedures. Less time required toperform these procedures generally correlates with a lower risk ofcomplications and mortality. When artificial cardiopulmonary assistanceis required, the priming and bringing into operation of a heart-lungmachine can be time consuming and requires medical staff specialized inperfusion.

Additionally, during machine priming, a liquid is used to fill theblood-conducting components of the heart-lung machine. The primingliquid must be vented or deaerated prior to connection with thepatient's vascular system and initiating heart-lung machine operation inorder to eliminate air bubbles, which can cause thrombosis. When such anextracorporeal blood circuit is used, air bubbles may form inside theblood circuit and air present in the blood circuit while putting theextracorporeal blood circuit into operation can enter into the blood. Anair bubble entering into the patient's blood circulation can cause afatal air embolism in the worst case. Air bubble detectors can detectair bubbles in the extracorporeal blood circuit to trigger a visual oracoustic alarm signal so that the blood supply to the patient can bestopped. Subsequently, medical personnel on hand must act as fast aspossible to eliminate the problem.

The apparatus and methods of the present invention overcome theaforementioned limitations of prior art heart-lung machines by providingfor a compact and portable heart-lung machine that can be primed andready for operation in less than 10 minutes with little or no humanintervention. The present heart-lung machine may be selfcontained andinclude an internal power supply, and/or may be connected to an externalpower supply such as an on-board power supply of an emergency land, air,or sea transport vehicle. Furthermore, no perfusion specialist isrequired for set up or operation and, in some embodiments, the machinemay be constructed to meet requirements for regulatory approval fortransport and mobile use. The machine may for instance in particularmeet requirements of the EN 1789 standard for use in humid environments,water subjection, and pass shake and crash tests involving up to 10 gforces.

The present invention is made possible, in part, by a number ofadvancements in heart-lung machine technology including a fast-closingclamp, a fast-priming extracorporeal blood oxygenation, deaeration andcirculation system, and an air bubble detection system, which aredescribed in co-assigned U.S. application Ser. Nos. 11/284,515 filedNov. 22, 2005; Ser. No. 11/366,342, now U.S. Pat. No. 7,597,546 filedMar. 02, 2006; Ser. No. 11/366,914, now U.S. Pat. No. 7,367,540 filedMar. 2, 2006; and Ser. No. 11/544,524 filed Oct. 30, 2006, which areincorporated by reference herein in their entirety. The apparatus andmethods of the invention are also made possible, in part, by amultistage air removal system and various other components andprocedures described herein.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention is a method for providing extracorporealblood circulation to a patient by connecting the patient's circulatorysystem to a heart-lung machine that is configured for rapid filling andpriming by a priming fluid as well as rapid and safe transition to anoperational mode. The heart-lung machine comprises a base module and apatient module with pivot means at the base module and/or at the patientmodule to pivot the patient module relative to the base module about ahorizontal axis from a filling position into an operating position.

In a second aspect, the invention is a method for providingextracorporeal blood circulation to a patient by connecting thepatient's circulatory system to a heart-lung machine that automatically(i.e. without human intervention) detects and eliminates automaticallyair bubbles in blood conducting components of the machine, redirects theblood flow through the blood circulating components to prevent thebubbles from entering the patient's circulatory system, removes thebubbles from the circulatory system and, once air bubbles are no longerdetected, resumes normal operation. This increases safety with aportable device for the provision of an extracorporeal blood circuitsuch as is described in U.S. patent application Ser. Nos. 11/284,515 and10/839,126, which are incorporated by reference herein in theirentireties.

In a third aspect, the invention is a method for providingextracorporeal blood circulation to a patient by connecting thepatient's circulatory system to a heart-lung machine that comprises afast acting clamp configured to close an arterial line when a bubble isdetected in the blood circulating components of the heart-lung machine.

In a fourth aspect, the invention is a method for providingextracorporeal blood circulation to a patient by connecting thepatient's circulatory system to a heart-lung machine that comprises ahose roller pump configured to remove air from a blood reservoir in theheart-lung machine.

The heart-lung machine may be handled by any trained hospital staff, andthere is no need or necessity of a clinical specialist, such as aperfusionist, or cardio technician, to be present for operation of theheart-lung machine. Automated activities, including fastpriming, airbubble detection, air removal system, etc. are necessary for theheart-lung machine to be operated safely without a perfusionist orcardio technician present.

The heart-lung machine is further a mobile, self-contained heart-lungmachine and, in some embodiments, comprises a plurality of modules,including for example two or three modules.

Advantageous embodiments of the invention are described in thedescription, in the drawings and in the dependent claims. Further areasof applicability of the present invention will become apparent from thedetailed description provided hereinafter. It should be understood thatthe detailed description and specific examples, while indicating thepreferred embodiment of the invention, are intended for purposes ofillustration only and are not intended to limit the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a portable heart-lung machine;

FIG. 2 is a perspective view of the control module of the heart-lungmachine of FIG. 1 connected to a mount of the base module;

FIG. 3 is a perspective view of some blood-conducting components of thepatient module in the filling position;

FIG. 4 is the representation of FIG. 3 in the operating position, butviewed from the rear; and

FIG. 5 is a diagram showing the individual components of a heart-lungmachine according to the invention.

FIG. 6 shows a schematic representation of the individual components ofa heartlung machine according to the invention.

FIG. 7 is a lateral section through a fast closing (quick action) clamp.

FIG. 8 is a lateral plan view of a fast closing clamp.

FIG. 9 is a plan view in the direction III indicated in FIG. 8.

FIG. 10a is a detail of the sectional view of FIG. 7.

FIG. 10b is a schematic cross-sectional view through Line IVa-IVa ofFIG. 10 a.

FIG. 11 is a schematic of a fast closing clamp not shown in FIGS. 7-9.

FIG. 12 is a side view of a peristaltic hose pump.

FIG. 13 is a mating piece of a hose pump.

FIG. 14 is a support element of a hose pump.

FIG. 15 is a support plate of the hose pump.

FIG. 16 is a perspective view of a side of a drive plate of a hose pump.

FIG. 17 is a perspective view of the drive plate of FIG. 16 on that sidewhich is remote from the support plate.

FIG. 18 is a section through the drive plate of FIGS. 16 and 17 alongthe line VIIVII.

FIG. 19 is an enlarged representation of a coupling device of a hosepump.

FIG. 20 is a diagram of an exemplary multi-stage air removal system.

FIG. 21 is a flow chart showing method steps exemplary of the presentmethods.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, the apparatus and methods involve a heart-lungmachine configured for rapid filling and priming by a priming fluid aswell as rapid and safe transition to an operational mode. The heart-lungmachine comprises a base module and a patient module with pivot means atthe base module and/or at the patient module to pivot the patient modulerelative to the base module about a horizontal axis from a fillingposition into an operating position.

The patient module can be pivoted in a guided manner relative to thebase module by the pivot means, whereby the position and orientation ofindividual components of the extracorporeal blood circuit is modified sothat air bubbles, which cannot escape while the machine is in thefilling position, can be removed from the system at or after thetransition to the operating position via venting lines. The filling andventing of the patient module can take place in approximately less than10 minutes, whereas comparable apparatus in accordance with the priorart require approximately 20 minutes for this procedure.

An automated, even quicker priming may be provided by apparatus andmethods described in concurrently filed patent applications of the sameapplicant as the present application having obtained application numbersEP10194069.0, EP10194070.8, and EP10194071.6 (which correspond to U.S.Provisional Application Nos. 61/420,758; 61/420,760 and 61/420,763,filed on even date herewith), which hereby are incorporated herein byreference in their entirety for all purposes. Embodiments of theseapparatus and methods when incorporated in the present invention have anumber of advantages, including fully automatic priming and air removal,while the below described (90 degree) pivoting process for priming isnot necessary.

In one preferred embodiment, there is approximately 90° between thefilling position and the operating position, which has the advantagethat any air bubbles can reliably escape from the blood-conductingcomponents. A blood reservoir is provided in the patient module and isarranged at an inclination of approximately 45° to the horizontal bothin the filling position and in the operating position. This has theconsequence that the blood reservoir again has the same orientationrelative to the horizontal after a rotation of the patient module by 90°so that the same flow conditions result inside the reservoir before andafter the pivoting. A centrifugal pump head having a central inlet and atangential outlet can be arranged in the patient module such that theinlet is oriented vertically upwardly in the filling position andhorizontally in the operating position. In this manner, the pump headcan be filled with priming liquid from above without air bubblesremaining in the pump head during this process. It can likewise beadvantageous in this process to provide the centrifugal pump head with atangential outlet, which is arranged at the bottommost position of thecentrifugal pump head in the operating position. This ensures that airis not pumped into the patient's circulatory system by the centrifugalpump when the pump is in the operating (operational) position.

The heart-lung machine may comprise, an arterial filter having a ventingoutlet that can be arranged in the patient module such that the ventingoutlet is oriented horizontally in the filling position and verticallyupwardly in the operating position. Consequently, air inside thearterial filter, which is still present in the filter after the fillingwith priming liquid, can escape upwardly via the venting outlet after apivoting into the operating position.

The pivot means provided can be provided in the most varied designs,such as a mount for the patient module pivotally supported at the basemodule. In this case, the patient module only has to be coupled to themount in order to permit a guided pivot movement. It is particularlyadvantageous in this process for the pivot means to include a guideprovided at the mount and at the patient module. In this case, thepatient module can also be used to ensure the guided pivot movement. Itis also possible to connect the patient module to a further module, forexample to a control module, and to fasten the unit of the patientmodule and control module to the mount. In this case, the guide can beprovided at the mount and at the control module. It is also possible,for example, to provide a pivot bearing at the base module into whichthe other module or other modules are inserted.

The patient module is preferably in the operating position after beingplaced onto the base module since, in this case, a fast removal of thepatient module from the base module is ensured without pivoting havingto be carried out beforehand. The base module may comprise a devicestand, which is provided with a pivotal hook to hang the apparatus onthe frame of a patient's bed. The control module and the patient modulemay also be integrated into a stand alone unit that is operated withoutthe base module. In some embodiments the hook is thus not present, whichmay provide for an alternative that is advantageous for sometransportation situations.

A method for putting the heart-lung machine into operation comprisesbringing the patient module into the filling position, in which fillingposition the blood-conducting components are filled with a primingliquid. The patient module is subsequently pivoted relative to the basemodule, preferably by about 90°, into the operating position. The pumphead provided in the patient module can be driven prior to the pivotingin order to pump the already filled-in priming liquid and thereby tofurther vent the blood-conducting components.

One embodiment of the heart-lung machine shown in FIGS. 1 to 4, iscomposed of three modules: a base module B comprising a device stand 10,a control module S and a patient module P comprising extracorporealblood-conducting components. The patient module P is coupled via latchelements (not shown) to the control unit S to form a unit and this unit,consisting of the control module S and the patient module P isreleasably latched to a mount 12 of the base module B.

As FIG. 1 shows, the device stand 10 may be made from tubular materialand has a pivotal hooking means 14 at its upper side which is bent toform a hook at its upper side to permit hanging to a frame of apatient's bed. The pivotal hook 14 can be pivoted downwardly by 180°from the position shown in FIG. 1 and can be plugged into two holdingclips 16, 17 so that the pivotal hook 14 is not in the way of themounting of the control module S and of the patient module P.

The device stand 10 is permenantly connected to a carrier element 20 ofthe base module B which has a plug socket 22 for a mains cable. Themount 12 is pivotally supported in the carrier element 20. An operatingpart 24 is foldably fastened to the left hand side of the carrierelement 20 in FIG. 1 and has a touch screen 26 which represents an inputand output means for a control device (computer) provided in the basemodule.

The carrier element 20 and the non-folded operating part 24 form anannular jacket for the unit of mount 12, control module S and patientmodule P. The operating part 24 must be unfolded open to the left fromthe position shown in FIG. 1 to mount or remove the unit of controlmodule S and patient module P.

FIG. 2 shows the mount 12 of the base module B of FIG. 1 to which thecontrol module S is releasably connected by means of latch connections28, 30. The patient module P is not shown in FIG. 2 for a simplifiedrepresentation. A unit of control module S and patient module P mustalways be plugged onto or removed from the mount 12 in operation. Thecontrol module S supplements the disk-segment shaped geometry of themount 12 and a handle 32 is located at the upper side of the controlmodule S with which the unit of control module S and patient module P,on the one hand, but also the whole heart-lung machine, on the otherhand, can be handled when the three modules are fastened to one anotheras shown in FIG. 1.

To pivot the patient module P relative to the base module B about ahorizontal axis from a filling/priming position into an operatingposition, the mount 12 of the base module B is equipped with two guiderails 34 which are parallel, provided at the outer periphery andcooperate with adjoining guide rails 36 of the control module S. Theguide rails 34 and 36 form a continuous guide structure with the aid ofwhich the unit of mount 12, control module S and patient module P can bepivoted relative to the base module B. The guide rails 34 of the pivotmount 12 are provided with a cut-out 38 with whose aid the pivot mount12 can be guided over two rollers (not shown) provided at the carrierelement 20 so that the pivot mount 12 can be pivoted on the supportelement 20 of the base module B. The toothed arrangement recognizable inFIG. 2 serves for the engagement of a damping mechanism ensuring auniform and damped pivot movement.

To assemble the pivot mount 12 with the support element 20, the pivotmount 12 is first brought into a substantially vertical position and thecut-outs 38 are guided via the rollers (not shown) provided at thecarrier element 20, whereupon the pivot mount 12 can subsequently bepivoted into the position shown in FIG. 1. After the folding open of theoperating part 24, the previously assembled unit of control module S andpatient module P can be latched on the pivot mount 12. To pivot thepatient module P from the now present operating position into a fillingposition, the now formed unit of control module S, patient module P andpivot mount 12 can be pivoted by 90° by pivoting down the handle 32 sothat the control module S is in the position in which the pivot mount 12was previously located. In this filling position, the blood-conductingcomponents of the patient module P are in the position and orientationshown in FIG. 3 with respect to the horizontal.

FIG. 3 shows some blood-conducting components of the patient module,with the patient module P having been rotated about 90°counterclockwise, starting from FIG. 1. The view shown in FIG. 3corresponds to a view from the other side of the patient module P incomparison with FIG. 1. The wall 40 of the patient module P standingperpendicular in FIG. 3 is thus disposed parallel next to the pivotmount 12, whereas the horizontally oriented wall 42 adjoins the controlmodule S. Furthermore, a plurality of hose connections are now shown inFIG. 3 for a better clear view. Reference numeral 44 designates acentrifugal pump head having a central suction inlet 46 and a radialoutlet 48 shown by broken lines in FIG. 4.

An approximately parallelepiped shaped blood reservoir 50 is installedat a position of 45° in the patient module P and its outlet 52 isconnected to the inlet 46 of the centrifugal pump head 44 via a hoseline (not shown). Venting lines 54 are located at the upper side of theblood reservoir 50. The inlet into the blood reservoir 50 coming from avenous connection is arranged approximately at the centre of the bloodreservoir and cannot be seen in FIGS. 3 and 4. It can be recognized inFIGS. 3 and 4 that an arterial filter 56 is provided in the patientmodule P which has a cylindrical shape, with a tangential inlet 58 and acentral axial outlet 60 being provided. A venting connection 62 isprovided centrally at the end face of the filter disposed opposite theoutlet 60.

Further components shown of the patient module P are an oxygenator 64and various connection elements which are provided at the wall 42disposed adjacent to the control module S and which serve for thecooperation with terminals, sensors or plug connections, since allblood-conducting components are provided in the patient module P,whereas control components such as the pump drive, valves and otherelectrical control elements are arranged in the control module S. FIG. 4shows the representation of FIG. 3 in the operating position, whichcorresponds to the representation of FIG. 1 in which the control moduleS and the wall 42 of the patient module P contacting it are orientedvertically.

As a comparison of FIGS. 3 and 4 shows, there is 90° between the fillingposition (FIG. 3) and the operating position (FIG. 4), with the bloodreservoir 50 provided in the patient module P being arranged in bothpositions at an inclination of 45° to the horizontal, since it isinstalled at 45° in the patient module. The centrifugal pump head 44 isarranged such that the central inlet 46 is oriented vertically upward inthe filling position (FIG. 3) and horizontally to the side in theoperating position (FIG. 4). The outlet 48 (not shown in FIG. 3) of thepump head 44 is arranged at the bottommost position of the centrifugalpump head 44 in the operating position shown in FIG. 4 so that theoutlet 48 lies beneath the inlet 46.

The arterial filter 56 is also arranged within the patient module suchthat the venting outlet 62 is oriented horizontally in the fillingposition and vertically upwardly in the operating position (FIG. 4). Theinlet 58 is oriented vertically downwardly in the filling position andhorizontally in the operating position, whereas the outlet 60 isoriented horizontally in the filling position and vertically downwardlyin the operating position.

FIG. 5 shows the different components of the heart-lung machine inaccordance with the invention in which the patient blood coming from avenous connection V is guided via a line 70 into the blood reservoir 50and flows from there via the outlet 52 into the inlet 46 of thecentrifugal pump 44. It is pumped from there via the outlet 48 into theoxygenator 64 and flows from there via the arterial filter 56 to thearterial connection A and from there back into the body of the patient.An internal bypass, which can be switched via a valve 72, is designatedby reference numeral 71. Reference numeral 73 designates a valve for theinflow line PR with which priming liquid can be guided into the circuit.Reference numerals 74, 75, and 76 each designate pressure sensors.Venting valves are designated by reference numerals 77, 78, and 79, withthe valves 77 and 78 switching the vent paths into the upper region ofthe blood reservoir 50 not filled with blood and the venting valve 79controlling the venting from the blood reservoir. Reference numeral 80designates a bubble sensor, which controls an arterial quick actionclamp 82 provided in the arterial outlet A if air bubbles are detected.Reference numeral 84 designates a flow sensor and reference numeral 86an electrical interface. The oxygenator 64 is provided with inflow linesand outflow lines for water and oxygen to effect an enriching of theblood with oxygen and a temperature control of the blood. In some casesthe blood temperature may be controlled to maintain normal bodytemperature, while in other cases, such as slowing the heart rate duringCABG, the temperature of the blood may be reduced.

To put the heart-lung machine described above into operation, startingfrom the representation of FIG. 1, the pivotal hook 14, if present, isfirst pivoted downwardly by 180° and the operating part 24 is folded tothe left. Subsequently, the total unit consisting of the control moduleS, the patient module P and the pivot mount 12 can be pivotedcounterclockwise so that the filling position is reached.

Priming liquid, which first (ct. FIG. 5) fills the blood reservoir andfrom there the centrifugal pump head 44, is supplied via the connectionPR in the filling position. The air located in the hosing is largelyremoved from the system in this process by the priming liquid arrangedabove the machine on filling, with air bubbles, however, remaining inthe upper region of the arterial filter 56 and in horizontal lineportions.

When the blood reservoir 50 is almost filled, the centrifugal pump head44 is set into rotation comparatively slowly, whereby the priming liquidis pumped through the system and further air residues are removed fromthe system. After a time period of approximately 20 seconds, furthercomponents—such as the oxygenator 64—are also filled with priming liquidso that the pump can be stopped and the unit of the control module S,patient module P and pivot mount 12 can be pivoted back into theoperating position.

After these pivoting back by 90°, that air can also escape which hadremained in the arterial filter 56 and in horizontal line portions. Acomplete filling and venting of the patient module can thus be achievedwithin a time period in the order of magnitude of approximately 6 to 10minutes.

In one embodiment, the heart-lung machine is a mobile, self-containedheart-lung machine comprising a battery power supply configured to powerthe heart-lung machine and particularly well suited for use in the fieldand for emergency use. In another embodiment, the heart-lung machine isa mobile, self-contained heart-lung machine comprising a battery powersupply and/or connectors for an external electrical power supply from atransport vehicle with the heart-lung machine configured to operate onbattery power and/or the external electrical power supply of thetransport vehicle.

In a second embodiment, the apparatus and method of the inventioninvolve a heart-lung machine comprising a blood reservoir, a blood pump,and a bubble detector for the detection of air bubbles between venousand arterial connections to the patient circulatory system. Bloodentering at the venous connection is pumped by the blood pump throughthe blood reservoir and, optionally, through further blood-conductingcomponents via the bubble detector to the arterial connection. Anarterial line located downstream of the bubble detector leads to thearterial connection and can be closed by an arterial quick action clamp.If the bubble detector detects an air bubble, the arterial quick actionclamp can be closed immediately so that the air bubble cannot enter intothe patient's blood circulation from the arterial line. Simultaneously,the blood pump is stopped, a bypass clamp is opened, and the blood pumpis re-started so that the blood is guided back into the blood reservoirthrough a bypass. The blood reservoir is connected to a further pump,which removes air from the top of the blood reservoir where air bubblescollect. As soon as the bubble detector no longer detects any airbubbles, the arterial quick action clamp is opened again and the bypassclamp is closed.

In accordance with an advantageous embodiment of the invention, a bloodoxygenator is arranged between the blood pump and the bubble detector.The oxygenator comprises a membrane that is impermeable to air bubbles,which contributes to the elimination of air in the system. An arterialfilter configured to collect and hold back microparticles which haveentered into the blood as well as gas bubbles can furthermore beprovided in front (upstream) of the bubble detector.

It is particularly advantageous for multiple blood-conducting componentsof the apparatus such as an oxygenator or an arterial filter to beconnected to the blood reservoir via a venting line that primarilyserves for flushing and venting during a priming process before theapparatus is placed into operation to pump blood. The venting linecomprises of clamps that can be used to open and close each venting lineduring priming. The venting clamps can, however, also be opened brieflyduring the operation of the apparatus at regular time intervals so thatair which has collected in the blood-conducting components is conveyedinto the blood reservoir. The air then rises to the surface in thereservoir and can be extracted by a pump provided for this purpose. Theventing line is connected to bloodconducting components in each case atthe side of the components disposed upwardly during operation so thatupwardly rising air bubbles migrate into the venting line. The regularventing of the blood-conducting components prevents the saturation ofblood with air and reduces the risk of an air bubble moving up to thebubble detector.

The pump extracting the air from the blood reservoir is preferably aroller pump, which can additionally have a clamping function. Such apump is described in U.S. patent application Ser. No. 11/366,342 andpermits the extraction of air from the blood reservoir with simplemeans, with it being ensured by the clamping function that no air canflow in the opposite direction, i.e. into the reservoir, even when thepump is switched off.

In accordance with an advantageous embodiment of the invention, the airextracted from the blood reservoir is pumped into an air containerarranged downstream of the pump extracting air from the blood reservoir.The total extracorporeal blood circuit thereby remains closed toward theoutside. A simple plastic pouch can serve as the air container.

Additional protection from air bubbles in the blood exiting theapparatus can be achieved by configuring the blood reservoir to comprisean inlet region separated from an outlet region by a screen unit whichis a membrane permeable for blood, but impermeable for air bubbles.

In accordance with a further advantageous embodiment of the invention,means are provided for the monitoring of the filling level of the bloodreservoir. A first sensor is preferably provided which detects whetherthe filling level reaches a first threshold value. A second sensordetects whether the filling level falls below a second threshold valuelying below the first threshold value. The corresponding information canbe passed on to an electronic control unit of the apparatus so that theroller pump can be switched on to extract air from the blood reservoirwhen the filling level falls below the first threshold value. The airwhich collects in the blood reservoir in bypass operation afterdetection of an air bubble or on a regular venting of blood-conductingcomponents is thus extracted automatically as soon as a predeterminedamount of air is present in the reservoir. As further security, theblood pump can be switched off if the filling level falls below thesecond threshold value. In this case, an alarm signal is simultaneouslyoutput. It is possible for the filling level of the reservoir to fallbelow the second threshold value, for example, if the venous connectionis not properly connected to the patient's blood circulation, but hasbecome loose so that air is pulled into the blood conducting components.In such cases, the described filling level monitoring switches the bloodpump off immediately.

In accordance with a further advantageous embodiment of the invention,the bypass clamp is opened at regular time intervals for a short periodto flush any pooled blood from the upstream side of the bypass clamp.This prevents coagulation of any pooled blood, which might then enterinto the extracorporeal blood circuit after the bypass clamp is openedand, in the worst case, subsequently enter into the patient's bloodcirculation via the arterial connection.

As a consequence of the described automated safety features present inthe heart-lung machine, an intervention by trained medical staff due toan error report is only necessary in an extreme emergency. In the normalcase, the apparatus in accordance with the invention can successfullyprevent air bubbles from entering into the blood circulation of thepatient connected to the apparatus without any human intervention.

A heart-lung machine according to the present invention may be used toprovide extracorporeal blood circulation and oxygenation to a patientundergoing conventional or keyhole CABG surgery. A heart-lung machineaccording to the present invention may also be required in some cases toprovide extracorporeal blood circulation and oxygenation duringpercutaneous angioplasty and/or placement of one or more drug-eluting ornondrug-eluting stents and/or during rotational or laser atherectomy,particularly if complications arise during the procedure such as theheart stopping or complications requiring the sowing or stopping of theheart. In the event of a complication during any of these procedures,the ability to quickly prime the heart-lung machine and bring it intooperation is of particular importance. Additionally, no perfusionist isrequired to prime or operate a heart-lung machine according to thepresent invention, which expands the conditions and locations underwhich extracorporeal blood circulation and oxygenation can be safelyprovided and procedures dependent thereon can be safely performed.

FIG. 6 shows a schematic of a heart-lung apparatus according to theinvention. Patient blood entering through a venous connection V isguided via a line 70 into a blood reservoir 50 and moves from therethrough an outlet 52 and into an inlet 46 of a centrifugal pump 44. Theinlet 46 is arranged centrally at the pump head of pump 44 and blood ispumped through a tangential outlet 48 arranged at the bottom most pointof the pump head of the centrifugal pump 44 and into an oxygenator 64 towhich an oxygen supply line is connected. Blood enriched with oxygen issubsequently filtered in an arterial filter 56 and finally flows, in thenormal case, through an arterial line 168 and via an arterial connectionA back into the patient.

The blood reservoir 50 is split into an inlet region 50 in and aseparate outlet region 500 out by a membrane 128 that is permeable forblood, but prevents air bubbles entering into the outlet region from theinlet region.

A bubble detector 80 is arranged between the arterial filter 56 and thearterial connection A. As long as it does not detect any air bubbles, anarterial clamp 82 in the arterial line 168 remains open, while a bypassclamp 72 remains closed. Blood flow can be continuously monitored byflow sensor 84, which measures blood flow in the arterial line 168.

If an air bubble is detected in the bubble detector 80, the arterialclamp 82 is closed immediately. The reaction path between the bubbledetector 80 and the arterial clamp is configured to be long enough thata detected air bubble cannot reach the clamp before the clamp is closed.The clamp 82 is preferably a fast-closing clamp, which closes in lessthan 300 ms, as described in co-assigned U.S. patent application Ser.No. 11/366,914. Clamp 82 is also called quick action clamp herein. Thesufficiently long reaction path and the speed with which the clampcloses advantageously prevents any air bubble detected by the bubbledetector 80 from reaching the arterial connection A. Simultaneously, theblood pump 44 is stopped, the bypass valve or clamp 72 is opened, andthe blood pump 44 is restarted, so that the blood, together with thedetected air bubble, flows via a bypass 71 back into line 70 and intothe blood reservoir 50.

In the blood reservoir 50, air bubbles rise upwardly so that blood islocated at the bottom in the reservoir 50 out, and air collects at thetop 50 in. Means 122 for the monitoring of the filling level of theblood reservoir are electronically coupled, for example via anelectronic control unit, to a hose roller pump 170 configured for theextraction of air from the reservoir. The hose roller pump 170 may be,for example, a hose pump as disclosed in U.S. application Ser. No.11/366,342. As soon as the monitoring means 122 of the filling level ofthe blood reservoir 50 reports that the filling level has fallen below afirst threshold value, the hose roller pump 170 is switched on to removeair from the top of the reservoir 50 in and pump the air into a wastecontainer 180. The hose roller pump 170 has a clamping function so thatit acts as a clamp if it is not actively pumping to prevent a backflowof air into the blood reservoir 50. If the filling level of the bloodreservoir falls further, despite the removal of air by the hose rollerpump 170, below a second threshold value, the centrifugal pump 44 isswitched off and an alarm, for example an audible and/or visible signalis output.

The oxygenator 64 and the arterial filter 56 are each connected to theupper region of the blood reservoir 50in by a venting line 96 providedwith venting valves 92, 94. The venting line first serves for theflushing and venting of the heart-lung machine during a primingprocedure before it is put into operation. In this procedure, a primingliquid is filled in via a priming connection PR and priming circuit(dashed line passing through valve 90) and the extracorporeal bloodcircuit is vented. The venting clamps 92 and 94 are normally closedduring the operation of the heart-lung machine but are, however, openedbriefly at regular time intervals, for example every 10 to 15 minutes,so that accumulated air in the oxygenator or the arterial filter isguided into the reservoir 50 for removal from the system.

Pressure sensors 74, 75 monitor the pressure before (upstream of) andafter (downstream of) the oxygenator. The measured values of thepressure sensors are forwarded to a pressure monitoring unit 127 via aconnection (not shown for reasons of clarity). An abnormal increase inthe pressure drop at the oxygenator 64 can be an indicator of cloggingby coagulated blood, and a need for action may be indicated, forexample, by triggering an audible and/or a visual signal. Additionally,the extraction pressure at which blood is extracted from the patientinto the line 70 is monitored using pressure sensor 76, which measuresthe pressure in the line connecting the blood reservoir 50 and the hoseroller pump 170. The measured result is likewise passed on to thepressure monitoring unit 127.

To avoid coagulation of standing or pooled blood in the bypass 71 inFIG. 6 beneath the bypass clamp 72 while the arterial clamp 82 is openand the bypass clamp 72 is closed, the bypass clamp 72 may be opened atregular time intervals for a short time to periodically flush the bypass71.

Arterial quick action clamp 82 shown in FIG. 6 is preferably a fastclosing clamp as shown in FIGS. 7-11. The sectional view of FIG. 7corresponds to the cross-section indicated by A in FIG. 9. The hose 201contacts a wall 203, which is formed for example by the rear wall of ahousing part receiving the hose. A clamp jaw 205 is configured to bebrought into a clamping position in the arrow direction by the fastclosing clamp, pinching the hose 201 closed.

A holding apparatus 207 comprises an inner hollow space in which theclamp jaw 205 is guided. In the embodiment shown, the clamp jaw 205 isan internal piston and the holding apparatus 207 is an external piston,with the internal piston 205 being displaceably received in the externalpiston 207 and the external piston 207 being displaceably received in ahousing 209. A spring 217 is supported against a seat 216 inside theexternal piston 207 and a seat 218 is supported at the externalperiphery of the internal piston 205, said spring being undercompressive tension in the open position of the internal piston shown inFIG. 7.

The spindle 219 of a spindle drive comprises an external thread 221 inthe region in which it engages into the external piston 207, which has acorresponding mating thread at the internal periphery where the spindle219 passes through it. The spindle 219 is rotatably held in the housing209 in a bearing 223. The spindle is connected to a toothed wheel 225via the grub screw 227. The toothed wheel 225 meshes with a toothedwheel 229 which, in turn, meshes with a toothed wheel 231 that isconnected via a grub screw 233 to the axis of an electric motor 235which is fixedly installed in a holding plate 237.

The toothed wheel 229 is rotatably supported in the holding plate 237.The housing 209 is permanently connected to the holding plate 237. Ahollow space 215 is located in the external piston 207 and balls 213 canpartly enter into it, which project radially out of the internal piston205 in the latched state.

FIG. 8 shows the fast closing clamp of FIG. 7 in a lateral plan view.The direction of view visible in the plan view of FIG. 9 is indicated byIII in FIG. 9. The internal piston 205 comprises a radially outwardlyextending abutment bar 239, which is guided in an elongate hole 238 ofthe housing 209 (FIG. 8).

FIG. 10a shows a detail of FIG. 7 in the region of the latch devicebetween the external piston 207 and the internal piston 205. The latchedstate is also shown in FIG. 10a . The tip of the blocking bar 211 liesin the axial cut-out 206 of the rear part of the internal piston 205. Inthis process, the tip presses balls 213 outwardly through radialopenings 214 in the internal piston 205, which partly enclose the balls213. The tip of the blocking bar 211 is made in ball shape and taperedtoward the front so that it can easily be pushed between the balls 213.In the embodiment shown, three of the radial openings 214 are providedwith corresponding balls 213 at an angle of 120° to one another. The twoother openings are therefore not visible in the sectional representationof FIG. 10 a.

The balls 213 engage into a cut-out 215 in the external piston 207. Inthe state shown, the internal piston 205 cannot move out of the externalpiston 207 to the right since the balls 213 are fixed in the cut-out 215of the external piston 207. If the blocking bar 211 is pulled out of theaxial cut-out 206 of the internal piston 205 to the left, the balls canmove into the axial cut-out 206 and the internal piston 205 can be movedout of the external piston 207 to the right by the force of the spring217. The inward movement of the balls 213 is in particular facilitatedby the chamfering 220 of the cut-out 215. The right hand end of thespindle 219 can be recognized in FIG. 10a with the thread 221, whichmeshes in an internal thread of the external piston 207.

Whereas FIG. 10a shows a section through the fast closing clamp in whicha ball 213 is sectioned precisely at the center. FIG. 7 shows a sectionin which no ball 213 is precisely cut. In this respect, the sectionalplanes of FIG. 7 and of FIG. 10a are tilted with respect to one anotherby 30° around an axis which is, for example, defined by the blocking bar211. This relationship is illustrated in FIG. 10b , which shows across-sectional view through Line IVa-Iva as labeled on FIG. 10a . Aview in an axial direction of the tip of the blocking bar 211 and of theballs 213 is shown in a schematic representation in FIG. 10b . 51 showsthe sectional plane of FIG. 7, while 54 shows the sectional plane ofFIG. 10a . The direction of view of the sectional plane, which is thesubject matter of FIG. 7, is designated by the arrows I in FIG. 10b .The direction of view of the sectional plane, which is the subjectmatter of FIG. 10a , is designated by the arrows IV in FIG. 10b . Theangle J3 indicated amounts to 60 degrees, whereas the tilt angle of thesectional plane amounts to 30 degrees.

FIG. 11 shows a part of the quick action, fast closing clamp not shownin FIGS. 710a , which is a mechanism that moves the blocking bar 211 inthe axial direction. The blocking bar 211 is connected via a hinge point212 to a rocker 241, which is rotatably supported at the point 243. Thisrocker is connected via a hinge point 249 to a metallic actuation bar247, which projects into an electromagnet 245. In this arrangement, thebar 247 moves to the right on a flow of current through theelectromagnet 245. The rocker rotates around the center of rotation 243and moves the blocking bar 211 to the left in the representation of FIG.11. A compression spring 248 biases the rocker 241, the actuation bar247, and the blocking bar 211 in the direction of their positions ofrest when the electromagnet 245 again has no current. The force of theelectromagnet 245 acts against the spring force of this spring 248.

When a bubble is detected in the hose 201, a signal is transmitted toput the electromagnet 245 under current for approximately 50 ms so thatthe actuation bar 247 moves into the electromagnet. The rocker 241rotates around the center of rotation 243 and pulls the blocking bar 211to the left. The blocking rod 211 thereby moves out of the axial hollowspace 206 (FIG. 10a ) of the internal piston 205. The internal piston205 is urged in the direction of the arrow (FIG. 7) by the spring forceof the spring 217. Since the blocking bar 211 no longer blocks the axialhollow space, the balls 213—facilitated by the chamfer 220—escape backinto this hollow space 206 and the latch connection between the internalpiston 205 and the external piston 207 is cancelled. The spring force ofthe spring 217 drives the internal piston 205 against the hose 201 andpinches it off against the rear wall 203 of the passage conducting thehose. It is, for example, sufficient to operate the electromagnet onlyfor approximately 50 milliseconds to trigger this action. The hose ispinched off after only around 100 milliseconds. The abutment bar 239guided in the longitudinal hole 238 in the housing 209 prevents theinternal piston 205 from being able to completely exit the housing 209on an unintentional triggering.

To move the internal piston back into its open position, the electricmotor 235 is switched on. The spindle 219 is driven via the toothedwheels 231, 229, and 225. The external piston 207 moves axially to theright out of the housing 209 by the spindle rotation. The internalpiston 205 is in the meantime still supported against the hose 201 orthe rear wall 203 of the passage. As soon as the external piston 207 andthe internal piston 205 are again completely pushed onto one another,the radial openings 214 in the internal piston 205 are again in theregion of the cut-out 215 inside the external piston 207. The tip of theblocking bar 211 can again push between the balls 213 which are in turnmoved radially outwardly through the openings 214 in the internal piston205. The blocking bar 211 is pushed into the axial cut-out 206 of theinternal piston 205 by the action of the spring 248 which acts on therocker 241 for this purpose. The balls 213 again engage into the cut-out215 in the external piston 207 as is shown in FIG. 10a and latch theexternal piston 207 and the internal piston 205.

If the electric motor 235 is operated in the reverse direction, thespindle 219 pulls the external piston 207 to the left in therepresentation of the Figures. The internal piston 205 is also movedback due to the latching of the internal piston 205 in the externalpiston 207 and the fast closing clamp again moves to its open position.The spring 217 again starts to tense while the external piston 207 isagain pushed over the internal piston 205 and stores energy for a newtriggering process. It is possible in this way to trigger a furtherpinching process as required on the returning of the internal piston 205together with the external piston if e.g. a bubble is again detected inthe extracorporeal circuit during the return of the internal piston 205.

The hose roller pump 170 in FIG. 6 is preferably a peristaltic hose pumpas shown in FIGS. 12-19. The pump, as shown in FIG. 12, comprises asupport plate 310, which can be installed in a fixed position, and abore through which a drive shaft 312 is rotatably inserted. The rightend of the drive shaft 312 in FIG. 12 can be driven by a drive (notshown), for example by an electric motor, whereby a rotor 314 attachedto the left end of the drive shaft 312 in FIG. 12 likewise rotates. Therotor 314 has a plurality of rollers 316 which are distributed over itsperiphery and which serve in a known manner to press fluid (e.g. air orblood) through a flexible hose (not shown).

A mating piece 318, shown in a perspective view in FIG. 13, is screwedbeneath the rotor 314 to the left side of the support plate 310 in FIG.12 and has two vertical blind bores 320 and 321, on the one hand, andtwo V-shaped grooves 322 and 323, on the other hand, which extend at anangle to the horizontal and extend inside one and the same verticalplane. The mating piece 318 furthermore has an approximatelysemi-circular opening in which the rotor can rotate freely.

FIG. 12 shows that a support element 326 above the rotor 314, which ismovable in the direction of the double arrow by a predetermined distancein the direction toward the rotor 314 or by a predetermined distanceaway from the rotor 314. FIG. 12 shows the pump with the support elementcompletely moved away from the rotor 314 by the predetermined distance.

Two guide pins 328 (only one is shown in FIG. 12), which are insertedinto the blind bores 320 and 321 of the mating piece, guide the supportelement 326. As FIG. 14 shows, the support element 326 likewise has twoblind bores 330 (only one is shown in FIG. 14) so that the supportelement 326 is guided by the guide pins 328. FIG. 14 shows that thesupport element 326 also has two V-shaped grooves 332 and 334 which,together with the grooves 322 and 323 of the mating piece 318, form aclamping device in which the hose can be clamped by a movement of thesupport element in the direction toward the rotor. A groove 336 providedat the rear side of the support element 326 serves for the insertion ofa metal piece to permit a contact free position detection with the helpof a sensor (not shown). A blind bore 338 is provided centrally at therear side of the support element 326. A pin 340 is inserted into thisblind bore, as shown in FIG. 12, extending through an elongate hole 341in the support plate 310 and simultaneously serving as an end abutmentfor the movement of the support element 326. The pin 340 projectssomewhat from the support plate 310 on the side thereof opposite to thesupport element 326 and the projecting end of the pin 340 is insertedinto a plain bearing 342 which is movable in a spiral groove 344 (FIG.17) of a drive plate 346.

The drive plate 346 is shown in more detail in FIGS. 16-18 and is placedfreely rotatable onto the drive shaft 312 via a plain bearing 348. FIG.17 shows a view of that side of the drive plate 346 which faces thesupport plate 310. The spiral groove 344 extends from the outer rim ofthe drive plate 346 in the direction of the center, with the spiralgroove extending over an angle of somewhat more than 180°. A ring groove350 is provided at the interior of the spiral groove 344 and receives afixed position cam guide 352, which is made integrally with the supportplate 310 (FIG. 15). FIGS. 15 and 19 show that the fixed position guidecam 352 has a rising and a falling flank of the same gradient. In thisprocess, the guide cam 352 is curved in the peripheral direction suchthat it fits into the ring groove 350 of the drive plate 346.

FIG. 16 shows the side of the drive plate 346 disposed at the bottom inFIG. 17. A curved recess is provided at this side of the drive plate346, which has two guide chamfers 354 and 356 whose lowest point formsan opening 358 through which a passage into the ring groove 350 iscreated. This passage serves for the passing through of a drive pin 360,which serves as a coupling member between the drive shaft 312 and thedrive plate 346.

FIG. 12 shows that a drive plate 362 is rotationally fixedly connectedto the drive shaft 312, with the drive pin 360 being resilientlysupported in a sleeve 364 provided at the drive plate 362 such that itis displaceably supported against the force of the spring in the axialdirection of the drive shaft 312. When the drive shaft 312 thus rotates,the drive plate 362 and also the drive pin 360 rotate together with it.In this process, the drive pin 360 presses against the drive plate 346due to the spring and the front end of the drive pin 360 runs on thedrive plate on an orbit which is indicated by a broken line in FIG. 16.If, in this process, the drive pin 360 moves into the region of theguide chamfers 354 and 356, the front end of the drive pin 360 moves onthese guide chamfers until it moves through the opening 358 in the driveplate.

The starting position is the situation shown in FIG. 12 in which thesupport element 326 has been moved away from the rotor 314 by thepredetermined distance. In this position, the drive pin 360 is locatedin the situation shown in FIG. 19 in which it projects through theopening 358 in the drive plate 346 and its front end lies on the fixedposition cam guide 352. If, in this process, the drive shaft 312 andthus the drive wheel 362 are moved against the arrow direction S, thedrive pin 360 is moved to the right in FIG. 19 and first runs on thefixed position cam guide 352 and subsequently on the guide chamfer 356of the drive plate 346 which merges constantly into the left hand flankof the fixed position cam guide 352. Subsequently, the drive pin 360runs on the orbit shown by a broken line in FIG. 16 until it again movestoward the guide chamber 354 and slides along on this until thesituation of FIG. 19 being the result. This means that the drive shaftcan be rotated as desired against the arrow direction shown in FIG. 19,without the drive plate 346 moving.

After a flexible hose has been inserted into the intermediate spacebetween the support element 326 and the rotor 314, the direction ofrotation of the drive shaft 312 is reversed and now runs in thedirection of the arrow S shown in FIG. 19. However, this means that thedrive pin 360 abuts the lower end of the guide chamfer 354, so that, ona further rotational movement, the drive plate 346 is taken along by thedrive pin 360 and likewise rotates in the direction of the arrow S. Inthis process, the front end of the follow pin runs along the fallingflank of the cam guide 352 until it revolves on the orbit shown by abroken line in FIG. 15.

On this rotation of the drive plate 346, the plain bearing 342simultaneously runs in the spiral orbit 344 and thereby moves in thedirection of the axis of rotation, whereby the pin 340 in the elongatebore 341 is likewise moved in the direction of the axis of rotation.Consequently, the support element 326 is moved by the predetermineddistance in the direction toward the rotor 314 such that the flexiblehose (not shown) is respectively clamped between the V grooves 322 and332, and 323 and 334. At the same time, the hose is clamped between thesupport element 326 and the rotating rollers 316 of the rotor 314 sothat a pump effect is achieved.

After a complete revolution of the drive pin 360 on the orbit shown in abroken line in FIG. 15, said drive pin moves from the right side in FIG.19 back up to the cam guide 352 and subsequently slides upwardly on thisuntil the front end moves onto the guide chamfer 354 of the drive plate346 constantly adjoining the cam guide 352 at this point in time. Thedrive pin 360 then slides further upwardly on this guide chamfer 354until the front end of the drive pin 360 revolves on the orbit shown ina broken line in FIG. 16. When the drive shaft is rotated further in thedirection of the arrow S, the drive pin 360 can revolve for any desiredlength of time without effecting a movement of the drive plate 346. Onlywhen the direction of rotation is reversed again does the drive pin 360again couple with the drive plate 346 in that it moves through theopening 358 and slides downwardly on the fixed position cam guide 352.The front end of the drive pin 360 subsequently again revolves once onthe orbit shown by a broken line in FIG. 15 until the situation shown inFIG. 19 is the result.

One important advantage of the present apparatus and methods overexisting apparatus and methods is the ability to quickly provideextracorporeal blood circulation and oxygenation without the need for aspecially trained operator. Quickly and automatically priming theapparatus and then placing the apparatus into an automated operationalmode required is enabled by the safety features described herein.Various combinations and configurations of Quick-action (fast closing)clamps, vent lines, filters, air removal pumps, and other componentsachieve a level of safety that permits the automation of the heartlungmachine and methods involving an automated heart-lung machine.

FIG. 20 shows a preferred embodiment of a multi-stage air removal systemproviding a level of safety that permits automated extracorporeal bloodcirculation and oxygenation. A screen filter with a suitable pore size,such as 120 IJm, separates the blood reservoir 50 into two sections(FIG. 5). Air bubbles having a diameter of greater than 120 IJm cannotpass through the screen from the venous blood input section of thereservoir to the output section of the reservoir.

An upper level fill sensor 122 a capable of distinguishing between gas(air) and liquid (blood) is connected to a roller pump 170 configured toremove air from the inlet portion of the blood reservoir. When the upperlevel sensor 122 a detects a liquid, the roller pump 170 is inactive.When the level of blood falls below the level of the upper fill sensor122 a, the sensor detects air and sends a signal to the roller pump 170,causing the pump to remove air from the top of the reservoir. Removingair from the reservoir results in a relative negative pressure withinthe reservoir that increases the rate at which blood is drawn into theinlet of the reservoir from the venous blood source.

A lower level fill sensor 122 b capable of distinguishing air from bloodis connected to a centrifugal pump 44 configured to pump blood from thereservoir 50 to an oxygenator 64. As long as the lower level fill sensor122 b detects blood, blood is pumped from the reservoir 50 to theoxygenator 64. When the lower level fill sensor 122 b detects air, itsends a signal to the centrifugal pump 44, causing the pump toimmediately stop pumping blood from the reservoir. This prevents thecentrifugal pump from emptying the reservoir and pumping air into thedownstream blood conducting components of the heartlung machine.

The centrifugal pump 44 has a central inlet and a tangential outlet atthe lowest point of the pump head with respect to gravity. Should airenter the inlet of the pump, the rotation of the pump causes liquid inthe pump to move toward the outer wall of the pump head leading to theoutlet while any air is moved toward the center of the pump head andprevented from reaching the outlet. Any air in the pump remains in thetop center portion of the pump head, which successfully prevents even asmall volume of air from reaching the downstream blood conductingcomponents of the heart-lung machine.

The oxygenator 64 has a separate ventilation system where air rises toand is removed from the highest point of the oxygenator 64. A vent line(purgeline) 96 a is connected to the top of the oxygenator andconfigured to carry the air away from the oxygenator. In a preferredembodiment, the oxygenator vent line 96 a carries air from theoxygenator 64 to the blood reservoir 50 as shown in FIG. 20.

Oxygenated blood moves from the oxygenator 64 to a vented arterialfilter 56. A vent line 96 b (purge line) is connected to the highestpoint in the arterial filter 56 and removes air that is trapped by thefilter. In a preferred embodiment, the arterial filter vent line 96 bcarries air from the filter 56 to the blood reservoir 50.

The air bubble sensor 80 (detector) is positioned downstream of thearterial filter 56 and communicates with a quick-action clamp 82positioned on the arterial line leading to the arterial connection A andto a bypass clamp 72 located on a bypass line (not shown). In normaloperation without air bubbles, the quick-action clamp 82 is open and thebypass clamp 72 is closed. In response to the detection of an air bubbleby the bubble sensor 80, the quick-action clamp 82 on the arterial linecloses immediately. Then the bypass clamp 72 on the bypass line opens todivert blood flow away from the arterial connection A and back to theblood reservoir 50 through the bypass line. As the bypass clamp is not aquick action clamp, but an ordinary hose clamp, it opens much slowerthan the quick action clamp 82 closes. Therefore, when the quick-actionclamp 82 is activated, the blood pump is simultaneously stopped, and thebypass clamp is “slowly” opened. After a short delay period, when thebypass clamp is open, the blood pump is re-started. This is made toensure that the running blood pump does not generate undesired highpressures in the blood conveying system against the closed quick actionclamp 82 and the closed bypass clamp 72. Thus leakage caused byoverpressure in the system is effectively avoided. Once no air bubblesare detected in the bypass flow by the air bubble sensor and apredetermined time interval has elapsed, the first and secondquick-action clamps revert to their normal operating positions.

A method according to the present invention comprises priming, orfilling, the heart-lung machine with a priming fluid such as sterilesaline. Once initiated, the priming can take place in an automatedmanner without human intervention. When primed and operational, themachine is fluidly coupled to the circulatory system of the patientthrough a vein to the venous coupling of the machine and through anartery to the arterial coupling of the machine.

The heart of the patient may optionally be slowed or stopped, ifnecessary. The blood returned to the patient is enriched with oxygen. Insome cases the blood temperature may be controlled to a body temperaturebelow normal body temperature and above a temperature where organs maybe damaged. Such a temperature range may currently be achieved byplacing the patient, or only the heart, in an ice bath during surgery.Controlling the blood temperature, and perhaps cooling the blood beforere-entering it into the patient via the venous vessel connection, is anelegant solution whereby the body temperature and/or the hearttemperature is much better controlled.

In the case of a coronary artery bypass graft a graft vessel, such as asegment of saphenous vein, an internal thoracic artery, or a radialartery is taken from the patient, a cannulae is sutured into the heart,and cardiopulmonary bypass using the heart-lung machine is initiated.The aorta is clamped and the heart is stopped and cooled to, forexample, 29° C. One end of the graft vessel is sutured a coronary arterybeyond a blockage to be bypassed. The heart is then restarted, the otherend of the graft vessel is sutured to the aorta while the heart isbeating, and the heart-lung machine is disconnected from the patient(FIG. 21).

The method may include the addition of drugs or other additives to theblood by way of the heart-lung machine. For example, an anticoagulantmay be added to the blood to prevent clotting while the heart isstopped.

In the case of percutaneous angioplasty or stent placement, a balloon isinflated inside a coronary artery to widen the passage or to expand astent that will widen the artery and support the artery in a more openconfiguration to improve blood flow therethrough. The heart may be, butis usually not stopped for percutaneous angioplasty or stent placement,but the expansion of the balloon catheter inside the artery may causethe artery to rupture and necessitate emergency heart surgery. Theheart-lung machine may be used in the event of such a complication orother complications that require the heart to be stopped or slowed. Theheart-lung machine may be, but need not be, primed as a precautionbefore a possible complication.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Apparatus and methodscomprising combinations of two or more of the various aspects and/orembodiments described herein and other variations are not to be regardedas a departure from the spirit and scope of the invention.

What is claimed is:
 1. A method for performance of a percutaneousangioplasty or stent placement procedure in a subject with concurrentcardiopulmonary support, said method comprising the steps of: a)obtaining an extracorporeal cardiopulmonary support device whichcomprises a venous blood inlet, a blood pump, a blood reservoir whichreceives blood from the venous blood inlet, an air extraction pumpassociated with the blood reservoir, a blood oxygenator which receivesand oxygenates blood from the blood reservoir, an oxygenated bloodoutlet through which oxygenated blood flows from the blood oxygenator, afilter for filtering oxygenated blood flowing through the oxygenatedblood outlet, a bubble detector for detecting the presence of bubbles inoxygenated blood flowing through the oxygenated blood outlet, a quickacting clamp located on the oxygenated blood outlet downstream of thebubble detector and control circuitry adapted to perform priming of thedevice, when initiated, in an automated manner without humanintervention, and to thereafter control operation of the cardiopulmonarysupport device without the need for a perfusionist; b) initiating thepriming, thereby causing the device to become primed in said automatedmanner without human intervention; c) positioning a venous cannula in avein of the subject and an arterial cannula in an artery of the subject;d) connecting the venous cannula to the venous blood inlet of theextracorporeal cardiopulmonary support device and connecting thearterial cannula to the oxygenated blood outlet of the extracorporealcardiopulmonary support device; e) positioning a balloon catheter havingan inflatable balloon in the vasculature of the subject and inflatingthe balloon to effect an angioplasty or stent placement; and f) if, uponinflation of the balloon, a complication selected from rupture of ablood vessel, cardiopulmonary arrest or cardiopulmonary insufficiencyoccurs, causing the extracorporeal cardiopulmonary support device tooperate, without a perfusionist, such that the blood pump pumps venousblood from the patient's venous vasculature, through the venous cannula,through the venous blood inlet, into the reservoir and from thereservoir to the oxygenator wherein the venous blood becomes oxygenated,and thereafter pumps the oxygenated blood from the oxygenator, throughthe oxygenated blood outlet, through the arterial cannula and into thepatient's arterial vasculature; wherein the priming is completed beforethe inflation of the balloon such that extracorporeal cardiopulmonarysupport device is primed and ready for use at the time the balloon isinflated.
 2. A method according to claim 1 wherein the device furthercomprises a sensor for sensing collection of air in the reservoir andwherein, during Step f, the extracorporeal cardiopulmonary supportdevice automatically causes the air extraction pump to extract air fromthe blood reservoir when a collection of air is sensed by the sensor. 3.A method according to claim 2 wherein said blood reservoir is separatedinto a lower blood-containing space and an upper air-containing space bya membrane that is permeable to blood but not to air bubbles and whereinthe sensor for sensing when air collects in the blood reservoir senseswhen a quantity of air has collected on one side of the membrane.
 4. Amethod according to claim 1 wherein the extracorporeal cardiopulmonarysupport device further comprises a recirculation conduit connecting theblood reservoir to the oxygenated blood outlet, upstream of the quickacting clamp, and a recirculation conduit clamp for closing therecirculation conduit; wherein, during Step e, the extracorporealcardiopulmonary support device automatically causes the quick actionclamp to close and the recirculation conduit clamp to open when thebubble detector detects a bubble, thereby causing oxygenated blood andthe sensed air bubble to recirculate from the oxygenated blood outletand into the blood reservoir where the air bubble is separated from theblood.
 5. A method according to claim 1 wherein the extracorporealcardiopulmonary support device further comprises a first pressure sensorfor sensing the pressure of venous blood upstream of the oxygenator, asecond pressure sensor for sensing the pressure of oxygenated blooddownstream of the oxygenator.
 6. A method according to claim 1 whereinperforation of a blood vessel occurs during performance of theangioplasty or stent placement and Step e is carried out for a timeperiod sufficient to allow emergency surgery to be performed to repairthe perforated blood vessel.
 7. A method according to claim 1 whereinthe heart becomes stopped or slowed resulting in cardiopulmonary arrestor insufficiency during performance of the angioplasty or stentplacement and Step e is carried out until sufficient cardiopulmonaryfunction is restored.